Apparatus for producing and dispensing aerated or blended fluid products

ABSTRACT

Apparatus for producing and dispensing an aerated product comprises a mixer which has a first inlet for receiving a fluid, a second inlet for receiving a gas, and an outlet. A relatively long continuous turbulence passage of relatively small cross section has one end positioned to receive the effluent from the mixer outlet and its other end spaced from the mixer outlet so that the effluent is subjected to confined turbulent mixing in the turbulence passage until the fluid product is discharged from the passage other end. If that product is to be cooled, the turbulence passage leads to a cooling area which cools and at least partially freezes the fluid product issuing from that passage. The invention has particular application to the making and dispensing of frozen yogurt and ice cream and allows for the service of individualized fresh portions in a variety of flavors and with little required cleaning.

RELATED APPLICATION

This application is a division of Ser. No. 08/154,747, filed Nov. 18,1993, now U.S. Pat. No. 05,433,967, which is a continuation-in-part ofSer. No. 07/740,725, filed Aug. 6, 1991, now U.S. Pat. No. 5,292,030which, is a continuation-in-part of application Ser. No. 564,719, filedAug. 6, 1990, now abandoned.

The present invention relates generally to the production and dispensingof aerated or blended fluid products. It relates more particularly to amethod and apparatus in which fluids such as two liquids or a liquid andair or other gas are mixed in selected proportions with the mixture,often cooled to a solid or semi-solid state, being dispensed as needed.While the invention may be used to produce a variety of products, it hasparticular application to the production and dispensing of frozenconfections such as ice cream and frozen yogurt. Consequently, we willdescribe the invention primarily in this context. It should beunderstood, however, that the invention has application to thedispensing of non-frozen and non-aerated products generally and to theintimate mixing of fluids.

BACKGROUND OF THE INVENTION

Aerated frozen products generally require the mixing of selected liquidingredients with a prescribed volume of air and freezing of theresultant mixture and dispensing of the finished product. Thedesirability of the finished product is often related directly to themanner and to the degree in which the air is metered and blended withthe liquid ingredients of the mixture and the manner in which theblended mix is frozen. The prior art is replete with examples ofapparatus for dispensing ice cream and other semifrozen dairy productssuch as soft ice cream and frozen yogurt.

Usually in such dispensers, the liquid mix containing, in the case ofice cream, ingredients such as cream, milk, condensed milk, syrup, etc.is delivered to a freezing chamber containing air or another non-toxicgas. In the freezing chamber, the mixture is slowly frozen andmechanically agitated by blades or the like to incorporate the air orgas in the mixture. This aeration is especially important and producesan increase in bulk corresponding to a decrease in the product specificgravity, thereby providing what is referred to in the ice cream industryas "over-run". The slow freezing and continuous agitation of results inthe formation of ice crystals and particles of varying size which candetract from the palatability of the resultant product.

The chamber typically serves both as the means of freezing and as areservoir from which individual servings are withdrawn. When the icecream is partially frozen to the proper consistency, it is pumped orextruded from the freezing chamber to the dispenser outlet for delivery,on demand, to containers such as cups and cones. Examples of suchapparatus are disclosed in U.S. Pat. Nos. 3,904,085; 3,954,126 and4,201,588.

The prior apparatus do not necessarily achieve dose control of over-run,which is a prime factor affecting product palatability and profit in themanufacture of ice cream and similar products. If there is not enoughaeration in the finished product, not only may the product be so denseas to be unpalatable, but also more liquid mix is required to make agiven volume of the product, thereby lowering profit. On the other hand,if there is too much air in the finished product, the product may beconsidered too "fluffy" and of lower quality and value. Also, in manystates there are regulations against providing excessive over-run incertain products to protect the consumer from being charged for aproduct that consists largely of air.

Conventional dispensers are usually dedicated to dispensing one or twoflavors of product and, in some cases, a combination ("twist") of thetwo. For example, in an ice cream shop, there may be one machine withtwo separate freezing chambers for making and dispensing chocolate andvanilla ice cream, a second two-chamber machine for making anddispensing strawberry and banana ice cream, a third machine dedicated tomaking and dispensing coffee and frozen pudding flavors, and so on. Thereason for this is that each chamber typically contains a volume of icecream greater than is required for a single serving. In order todispense a different flavor ice cream, that chamber must be emptiedbefore the new flavor can be made in that chamber and appear at theoutlet of the dispenser; additionally, the vat of preflavored mix fromwhich the material being aerated and frozen is drawn must also becleaned. While high volume ice cream shops and confectionery stores mayhave sales to justify the presence of several dispensing machinesdispensing many different products, smaller sales outlets can usuallyonly afford one or two such machines and are thus restricted in thenumber of flavors that they can offer to customers.

Further, because the product is typically formed in a quantity that isgreater than that to be dispensed at any one serving, the excess productremains in the chamber after formation and until the next serving isrequired. The excess is thus subjected to further mechanical beating byany blades in the chamber, as well as to excess freezing which promotescrystallization. Because of the quantity of the premixed flavors, andthe continuous freezing and beating of several quarts of the product,the freshness and palatability of the product may be adversely affectedin stores with slow sales of the product.

Another disadvantage of the prior dispensers is that they have manyinterior surfaces and moving parts that are difficult and time-consumingto clean and to maintain. At the end of each day or at other intervalsprescribed by local Health Department regulations, each dispenser mustbe purged of any remaining product, and its chamber walls, pumps, andother internal parts cleaned thoroughly to prevent growth of bacteriathat could contaminate product being delivered by the dispenser. Notonly is the cleaning operation expensive in terms of downtime, it isalso costly in terms of product waste and is an unpleasant and difficultjob to get employees to do properly.

There have been attempts to produce and dispense aerated frozen productson a continuous basis by atomization. In one example of this type ofdispenser, disclosed in U.S. Pat. No. 2,594,422, a liquid mix and aliquid refrigerant are mixed in a mixing chamber and fed through arotary emulsifier which forms a single liquid emulsion. The emulsion isthen jetted from a spray nozzle, into a separating chamber where theliquid refrigerant evaporates, effectively freezing adjacent droplets ofmix and thereby transforming them into flakes or a fine powder. Groupsof flakes then agglomerate into larger particles containing an interiorvoid. The refrigerant adsorbed on the interior surfaces of the void mayfurther expand in the separating chamber to increase the bulk of theparticles and thus decrease their density. The liquid refrigerantevaporated in the separating chamber is drawn off and reused. The frozenparticles fall into the chamber of a screw-type extruder whichcompresses the particles at a controlled rate to give the final productthe desired density and drives the frozen product to the dispenseroutlet.

The over-run is formed by, and limited by, the void space between flakesformed by mechanical agglomeration as opposed to actual entrapment ofair within the interior of an individual droplet. Thus, even though thatpatented dispenser uses atomization to make an aerated frozen product,the over-run is determined by the amount of liquid refrigerant adsorbedin the liquid mix before it is fed to the separator. In addition, theextruder is required to further reduce over-run and improve bodytexture.

Also that patented apparatus, like the other dispensers described above,has various internal surfaces and moving parts which must be cleaned inorder to keep that dispenser in a sanitary condition. Moreover, there isalways a supply of frozen product in the extruder chamber. As describedabove, this makes it impossible to change quickly from one productflavor to another and, if there is a change without disassembling andcleaning the machine, this results in a mixing of flavors.

SUMMARY OF THE INVENTION

Accordingly, it is an object of this invention to provide apparatuswhich uniformly mixes fluids to obtain a superior blended or aeratedproduct.

Another object of the invention is to provide apparatus for producingand dispensing an aerated product which does not require the maintenanceof a large volume of product within the apparatus.

A further object in the invention is to provide apparatus of this typewhich is simple in construction and is easy to make and maintain.

Still another object of the invention is to provide apparatus of thisgeneral type which facilitates changing substantially immediately fromone product mix to another to satisfy the demands of individualcustomers.

A further object of the invention is to provide apparatus for producingand dispensing individualized, small portions of freshly aerated frozenproducts on demand.

Yet another object is to provide apparatus for producing and dispensingaerated frozen products which is easy to clean and to maintain in asanitary condition.

Another object of the invention is to provide apparatus for making icecream and the like of high quality and whose over-run is closelycontrollable over a wide range.

A further object of the invention is to provide apparatus of thisgeneral type which occupies a relatively small amount of space whiledispensing multiple flavors.

Still another object of the invention is to provide apparatus forintimately dispersing a fluid in a liquid.

Yet another object of the invention is to provide a method of producingand dispensing an aerated product which enables close and consistentcontrol over the amount of gas entrained in the final product.

Still another object is to provide a method of making ice cream, yogurtand similar aerated frozen products which enables close control ofproduct over-run over a wide over-run range.

Other objects will, in part, be obvious and will, in part, appearhereinafter. The invention accordingly comprises the several steps andthe relation of one or more of such steps with respect to each of theothers, and the apparatus embodying the features of construction,combination of elements and arrangement of parts which are adapted toeffect such steps, all as exemplified in the following detaileddescription, and the scope of the invention will be indicated in theclaims.

Briefly, in accordance with this invention, aerated products such as icecream, frozen yogurt, or the like are produced and dispensed byatomizing a fluid such as a liquid product mix and a fluid such as a gasand thereafter thoroughly mixing them to form a smooth, relativelyhomogeneous product whose composition is controllable over a wide rangeof mixtures. In one embodiment of the invention, the first fluid, e.g.,yogurt, is atomized before it is mixed with the second. In anotherembodiment, the atomization occurs concurrent with the mixing. Inparticular, in the present invention, mixing is achieved by passing themixture or its ingredients, under pressure, through an extended conduitunder conditions such that turbulent mixing occurs. In particular, inthe formation of an aerated product such as ice cream or frozen yogurt,the atomization process breaks up the liquid ice cream or yogurt mixinto fine particles, while the confinement of the particles and airstream in the conduit creates turbulent mixing of those ingredientswhich causes the air to become very thoroughly admixed with the liquidmix particles. While the exact process is complex, we believe that thecontinuing, very dose confinement of the particles as they are forcedalong the conduit and while still largely in the liquid state causesthem to combine and coalesce to form larger liquid particles with theair entrapped and enclosed therein as though there were bubblessurrounded by a liquid "skin".

The amount of aeration in the product is a function of a number offactors, such as the length of the conduit, its inside diameter, thedischarge velocity from the mixing space into the conduit, the mixparticle size, the ratio of the gas to the mix, the volume flow rate,the mix density and viscosity, the mix surface tension, and thetemperature of the mix. The liquid product mix advantageously comprisesa neutral base of ice cream, yogurt or the like, together with one ormore flavorings and other additives as desired. During transit throughthe turbulent mixing passage, the flavoring and other additives arethoroughly admixed with each other and with the air to form a smoothrelatively homogeneous product of fine particles. Although the extent ofmixing may be controlled by varying one or more of these factors, wehave found that for the preferred embodiment described herein, theconduit length provides a convenient basis for control of the amount ofaeration.

In one embodiment of the invention, the conduit is oriented verticallyso that the aerated mix issuing from the conduit can drop through acooling chamber directly into a suitable container positioned under theconduit. In another preferred embodiment, the aerated mix from theconduit is distributed onto the outer face of a chilled drum or wheelthat is rotated at a selected speed. While on the drum, the mix freezesto form a coating on the drum. As the drum rotates, this coating isprogressively scraped from the drum and drops into a containerpositioned under the drum.

Different additives can be introduced into the aerated product stream byinjecting them into the liquid mix or gas stream or into the turbulentmixing passage, or can be dropped into the container as it is filledwith the frozen mix. Thus, for example, if the first product portionbeing dispensed requires an additive A1, the proper amount of thatadditive is injected into, e.g., the conduit for mixing with the liquidmix and gas comprising that first portion. If the next portion requiresan additive A2, that additive is injected into the mixing passage inlieu of additive A1, and so on.

The internal volumes of the mixing passage and the pipes injecting theadditives into that mixing passage are quite small relative to thevolume of the usual product portion being dispensed. Therefore, whenchanging additives, there is a negligible amount of carryover of theadditive from one portion into the succeeding portion. Even that minimalamount of carryover or "contamination" can be substantially eliminatedas will be described later.

The present apparatus and method thus enable the production of aeratedproducts on an "as-needed" basis without having to maintain a supply ofthe finished product in the dispenser. Even in the case of an aeratedfrozen product such as ice cream, as soon as the product is produced, itis conducted directly into a container; substantially none of theproduct remains in the dispenser. Therefore, the same dispenser candispense a variety of different ice cream flavors, for example, withoutthere being any appreciable flavor carryover from one serving to thenext. Also, in having minimal moving parts contacting the product and noproduct storage requirement, the dispenser can be maintained in asanitary condition with minimum effort and downtime.

The present turbulent mixing technique can also be used to thoroughlyblend other fluids such as two or more liquids, e.g., coffee and creamsoda, water and flavoring syrups, different color paints, differentcreams, etc. or a liquid with fluid particulate material, e.g., milk andpowdered chocolate, water and spackel powder, etc. or even two or moreslurries. Therefore, the invention should find wide use in a variety ofdifferent applications inside and outside the food industry.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and objects of the invention,reference should be made to the following detailed description of onepreferred embodiment of the invention, taken in connection with theaccompanying drawings, in which

FIG. 1 is an isometric view, with parts broken away, showing apparatusfor producing and dispensing an aerated frozen product according to thisinvention;

FIGS. 2 and 3 are diagrammatic views that help to explain certainaspects of the FIG. 1 apparatus;

FIG. 4 is a side elevational view showing another, preferred, embodimentof the invention;

FIG. 5 is a sectional view taken along line 5--5 of FIG. 4;

FIG. 6 is a fragmentary isometric view showing a portion of the FIGS. 4and 5 apparatus in greater detail;

FIG. 7 is a schematic diagram showing another apparatus embodiment, and

FIG. 8 is a diagrammatic view of another embodiment of the invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Referring to FIG. 1 of the drawings, apparatus in accordance with thepresent invention for producing and dispensing an aerated product, inthis example, a frozen product such as ice cream, is indicated generallyat 10. It comprises a mixing chamber defined, in this embodiment, by avertically oriented air atomizing nozzle 12 having a first inlet 12a forliquid, a second inlet 12b for air or other gas, and a single dischargeoutlet 12c. Connected to the inlet 12a is a conduit or tube 14 whichleads from a source (not shown) of the liquid to be aerated. In thisexample, that liquid is a more or less standard mix of the ingredientsfor making a frozen food product such as ice cream. The flow of fluidthrough pipe 14 to nozzle 12 is controlled by a solenoid-actuated valve16 in line with pipe 14.

The gas for aerating the liquid mix is supplied to nozzle 14 by a pipe22 leading from a gas source (not shown) which delivers the gas at apressure above atmospheric. In experimental apparatus demonstrating theinvention, pressures of from 5 to over 100 psi have been used. The gasmay be air or any other non-toxic gas customarily used to provideover-run or bulk in conventional ice cream products. The flow of gas tonozzle 12 is controlled by a solenoid-actuated valve 24 in line withpipe 22. The operations of valves 16 and 24 are controlled by outputsignals from a controller 26 which has an accessible key pad 28 by whichan operator can control the operation of apparatus 10.

The atomized mix issuing from the mixing chamber, i.e. from nozzleoutlet 12c, is not sprayed into an open space as usually happens withindustrial nozzles of this type. Rather, it is directed into one end ofa relatively long, e.g. 2 to 24 in., relatively small diameter, e.g.0.08 to 0.24 in. turbulent mixing passage in the form of a conduit 30wherein the effluent from nozzle 12 is subjected to considerableturbulence and buffeting because of passage through the conduit. Thus,in the conduit, there is violent turbulent mixing of the atomized mistparticles and the gas, as shown at T in FIG. 1, which apparently causesthe particles to coalesce forming somewhat larger particles while, atthe same time, entrapping the gas so that the gas is effectivelycontained within the particles. Consequently, the fluid issuing from thedischarge end 30b of conduit 30 is comprised of approximately uniformlysized, still relatively small aerated particles with the air enclosedwithin an outer generally continuous "skin" formed by the mix. Asexplained in more detail below, the dimensions of the conduit used forthe specific application are dependent on a number of factors, includingthe specific product mix, the desired production rate, the drivingpressure, atomizing nozzle size, desired aeration, and desired"wetness", among other factors. In general, the length of the conduitwill be at least several times the diameter of the conduit (orequivalent diameter, that is, the diameter of a conduit of cross sectionequal to that of a given circular cross section).

During passage through the cooling chamber, the particles are "flash"frozen in a few, i.e. 1 to 10, seconds due to the relatively high ratioof surface area to volume of the particles emerging from the conduit.The small particles emerging from the conduit, combined with the flashfreezing of each particle, produce a very uniform, smooth and idealizedproduct in terms of what is normally strived for in palatability.Further, it is calculated that the energy requirements of the processlie within the range of conventional freezing machines.

Referring again to FIG. 1, positioned below the turbulence conduit 30 isa vertically oriented tubular cooling chamber 34 which has a centralpassage 34a for receiving the discharge end 30b of conduit 30, thechamber extending an appreciable distance below the conduit. Formed inthe wall of chamber 34 is a helical passage 36 for circulatingrefrigerant through the chamber. The upper and lower ends of the passage36 are connected by pipes 36a and 36b to the outlet and inlet,respectively, of a refrigeration unit 38. Unit 38 may also be controlledby controller 26.

Spaced below the lower end of chamber 34 is a horizontal shelf or tray42 for supporting a container such as a paper or plastic cup C. Cup C isnormally positioned directly below the central passage 34a in chamber 34so that it is in position to catch or receive ice cream dropping underthe influence of gravity from the lower end of the chamber passage 34a.

Preferably, the diameter of chamber passage 34a is made sufficientlylarge that the aerated mix particles issuing from the conduit end 30a donot contact and coat the wall of that passage. This minimizes the needto clean that surface. The buildup of particles on that interior wallcan be further avoided by providing an air barrier or boundary layeradjacent to the passage wall. To provide such an air boundary layer,apparatus 10 includes, at the top of chamber passage 34a, a circularpipe 44 having a multiplicity of small holes (not shown) in itsunderside. Pipe 44 is connected to a gas source (not shown) by way of apipe 46 having an in-line solenoid-actuated valve 48 controlled bycontroller 26. When valve 48 is opened, e.g. just before each dispensingcycle, a downwardly directed cylindrical layer of air helps isolate thewall of passage 34a from the fluid issuing from conduit 30.

As an alternative means of providing the air barrier, chamber 34 may becomposed of spaced-apart inner and outer walls, with the former wallbeing porous, and pipe 46 delivering gas to the space between the walls.The gas issuing through the porous inner wall will tend to repel any mixparticles approaching that wall.

In accordance with this invention, apparatus 10 includes provision forallowing selection of the flavors of the ice cream to be dispensed byapparatus 10. This is accomplished by means of a tube 50 whichcommunicates with a manifold 52 having several, herein five, inletbranches 52a to 52e. Each of these branches is connected to a source(not shown) of an additive, e.g. chocolate, strawberry, vanilla, etc.,syrup. Solenoid-actuated valves 54a to 54e are included in the branches52a to 52e to enable selection of the additive or additives to besupplied to manifold 52. All of these valves are controlled by signalsfrom controller 26. The tube 50 connects to an upper end segment ofconduit 30 to supply the selected additive or additives to the fluid inconduit 30, although, alternatively, the connection may be made upstreamfrom conduit 30.

The components of apparatus 10 may be housed in a housing shown inphantom at 60 in FIG. 1, an appropriate opening 60a being provided in awall of housing 60 to provide access to the shelf 42 so that a cup C canbe positioned on the shelf as shown in FIG. 1.

Key pad 28 has selection keys or buttons 28a to 28e corresponding to thevalves 54a to 54e to enable the operator to select the flavor of the icecream product to be dispensed by apparatus 10. Controller 26 isprogrammed so that when the operator presses, say, key 28a, thecontroller 26 applies timed actuating signals to valves 16 and 24,thereby opening those valves so that non-flavored liquid ice cream mixand gas are fed to nozzle 12 in the proper ratio. As nozzle 12 spraysthese fluids into conduit 30, controller 26 sends a signal to valve 54aopening that valve so that additive 1, e.g. chocolate syrup, is injectedby way of manifold 52 into conduit 30, so that the additive is entrainedin the effluent from nozzle 12 and thoroughly mixed into the liquid mixbeing aerated in the conduit 30. The signals from controller 26 thatcontrol valves 16, 24 and 54a cause those valves to remain open for thetime required for the apparatus 10 to dispense a selected volume of icecream product, e.g. one portion or serving of chocolate ice cream, thatwill fill the cup C on shelf 42. Then valves 16, 24 and 54a close sothat substantially no additional fluid flows from the conduit 30.

The illustrated apparatus also allows for addition of liquid or solidmaterials to the frozen product in container C. For this, a pluralcompartment dispenser 68 is provided adjacent to chamber 34. Thedispenser has several compartments 68a which may contain variousmaterials such as chopped nuts, jimmies, chocolate syrup, etc. Inresponse to actuation of the appropriate key of key pad 28, controller26 causes the dispenser to dispense the selected material through acommon outlet tube 69 whose discharge end overlies container C. Thematerial will be incorporated into, or added to the top of, the productin container C depending upon when the dispensing is commenced andended.

As soon as the cup C has been filled, it can be removed and replaced byan empty cup. The operator can then fulfill the request of the nextcustomer. If that next customer wishes a different flavor ice cream,e.g. vanilla, the operator can depress the key pad key corresponding tothat flavor, e.g. key 28c. In response, controller 26, in addition toopening valves 16 and 24 as before, will open valve 54c so that vanillaflavoring will be fed to conduit 30 and entrained in the non-flavoredice cream mix issuing from nozzle 12.

The controller 26 may also be programmed so that the dispenser willdispense different size portions. Thus by depressing a certain key ofthe key pad, the operator may fill a pint-size container with theselected flavor ice cream. Depression of another key may dispense a halfpint of the product, and so on.

The internal volume of conduit 30 is very small, e.g. a small fractionof a cubic inch, so that any column of flavored product left standing inthat tube after each dispensing operation, is insufficient to materiallyaffect the flavor of the next full product portion being dispensed byapparatus 10. Further, by maintaining valve 24 open for a brief intervalafter stopping the flow of mix by closing valve 16, the conduit caneffectively be purged of remnant mix.

It should be noted that after each dispensing operation, branch tube 50and manifold 52 remain filled with liquid flavoring or syrup from theprevious cycle. The amount of same can be minimized by minimizing thestanding volumes between valves 54a to 54e and conduit 30, i.e. thelengths and internal diameters of tube 50 and manifold 52 so that theamount of syrup that is carried over from one portion to the next issuch a small percentage of the total volume of each portion that thereis no discernible flavor carryover, i.e. color or taste, from oneportion to the next.

However, apparatus 10 includes provision for avoiding even that minimaladditive carryover. More particularly, a conduit 56, having an in-linesolenoid actuated valve 58, is connected between pipe 22 upstream fromvalve 24, and the end of manifold 52. At the end of each dispensingcycle, controller 26 issues a signal to valve 58 which opens that valvefor a sufficient time to purge manifold 22, tube 50 and conduit 30 oftheir liquid contents.

Still referring to FIG. 1, it is important to appreciate that apparatus10 has no moving parts such as emulsifiers, extruders, etc. that couldbreak and require service. Furthermore, there are very few surfaces thathave to be cleaned to maintain the machine in a clean and sanitarycondition. The nozzle 12 and conduit 30 have very small internal volumesand these components can be cleaned by flushing the nozzle and tube withgas supplied through pipe 22. Similarly, tube 50 and manifold 52 can bepurged of residual additive by flushing them with gas supplied by pipes22 and 56. Preferably, for this purpose, the key pad 28 includes a keywhich the operator can actuate at the end of the day or at otherappropriate times which will cause controller 26 to open valves 24 and58 without opening the other valves so that gas under pressure scrubsthe internal surfaces of those parts.

Additionally, if desired, pipe 14 may be provided with a branchdownstream from valve 16 and leading from a source of hot steam or othersanitizing fluids (not shown) so that by depressing an appropriate keyof the key pad 28, the operator can cause controller 26 to open a valvein that branch so that steam or other sanitizing fluid will flow throughnozzle 12, conduit 30 and chamber passage 34a to sanitize theirsurfaces. The only parts of apparatus 10 that may require manualcleaning from time to time are the surface of chamber passage 34a andthe surfaces of shelf 42.

When making an aerated frozen product such as ice cream or frozenyogurt, it is very important to be able to control the over-run becausethis directly affects the cost and palatability of the product asdiscussed at the outset. Apparatus 10 will readily produce product withover-runs ranging from about 5% to 80% or higher. Thus, for example, itcan make gourmet ice cream which has a preferred over-run of 5-25%, softice cream with a preferred over-run of about 30-50%, and ice milk orother products whose over-run should be about 50-80% or higher.Furthermore, for each product, the over-run can be controlled closely tomaximize profit while maintaining product quality and palatability.

The flow rates of the gas and liquid mix supplied to nozzle 12, and thelength and temperature of cooling chamber 34, e.g. 6 to 10 in. and -40°to 0° F., respectively, for example, are strongly interdependent asregards the number and size of aerated particles that freeze in chamber34 before falling into container C. However, these factors primarilyinfluence product wetness/dryness which has more to do with productquality than with over-run. For example, increased air pressureincreases over-run slightly. But it also increases particle velocity andthus reduces the percentage of the particles that freeze in chamber 34so that a more moist product is dispensed. On the other hand, anincreased block temperature results in a wetter product with lessover-run. In both cases, the resultant product is wetter and, therefore,compromised in quality.

However, the length of the turbulent mixing passage or conduit 30, byitself, has been found to have a strong influence on the amount ofover-run in the product being dispensed. As the length of that conduitis increased up to some maximum, there is an increase in the efficiencyof gas entrapment in the liquid mix particles flowing through theconduit. Consequently, more gas is incorporated in the mix particlesissuing from the conduit, resulting in a frozen product with greaterover-run.

FIG. 2 is a graph showing, in the case of one particular example, thevariation in the over-run with conduit length when the mix particlesfrom the conduit were passed through the conduit at a constant flowrate. As seen from FIG. 2, in that example there was a smooth andsubstantial increase in over-run as the conduit length was increased.The curve indicates that adjustment of the length of the turbulenceconduit caused a variation in the product over-run from about 5% to over80%. In apparatus 10, the length of conduit 30 may be adjusted bychanging conduits, or more conveniently, by making the conduitextensible, i.e. as two telescoping sections, as indicated by the dashedline L across conduit 30 in FIG. 1.

The inside diameter of conduit 30, on the other hand, is not a variableespecially suitable for over-run control. This is shown by FIG. 3 whichis a graph plotting over-run verses conduit diameter in this oneexample. The curve there shows that with that particular production flowrate, there is only a small range of conduit diameters, i.e. 0.08 to0.12 in., at which good quality product is produced. Outside that range,the product is too moist and has too little body.

Refer now to FIGS. 4 and 5 which illustrate another embodiment of myinvention shown generally at 80. Here, the product mix and gas areatomized in a plural port fitting rather than in a nozzle prior to beingintroduced into the turbulence conduit. Also, the effluent from theturbulence conduit, instead of dropping through a cooling chamber into acontainer, is deposited onto the outer surface or face of a rotarychilling drum. The frozen product is then scraped from the drum anddeposited in a container.

Apparatus 80 comprises an upstanding support 82 which supports at itsupper end a hollow fluid-tight rotary drum 84 which may be in the orderof 2 feet in diameter and 4 inches wide. For ease of illustration, wehave shown drum 84 supported on both sides by a pair of tubular axles 86and 88 which project from opposite sides of the drum at the drum axis.One end segment of axle 86 is mounted to the support; the opposite endof that axle is connected to the drum by way of a rotary union or joint92. Also, as shown in FIG. 4, axle 86 has a tubular extension 86a insidedrum 84 which is bent up so that the extension extends almost to the topof the drum.

The tubular axle 88 has one end which is mounted to the left side of thedrum, that end also projecting slightly into the interior of the drum.The opposite end of axle 88 connects to one side of a rotary joint orunion 94, the opposite side of which is connected to a tubular shaft oraxle 96 mounted to support 82. The outer ends of axles 86 and 96 areconnected to pipes 98 and 102, respectively. These pipes extend down tothe input and output, respectively, of a refrigeration unit 104 presentat the bottom of support 82. When unit 104 is in operation, refrigerantis circulated up through pipe 102 through rotary joint 94 and axle 88into drum 84. The refrigerant fills the drum up to the level of theupper end of the extension 86a inside the drum and drains through thatextension and through axle 86 down through pipe 98 back to therefrigeration unit 104.

In practice, drum 84 may be supported from the back side only by way ofa coaxial tubular axle instead of axle 88 so that refrigerant issupplied to and drained from the drum through the back of the drum. Thismakes it much easier to clean the drum.

At least the cylindrical surface 84a of drum 84 is made of a highlythermally conductive material such as stainless steel or nickel-platedaluminum so that the liquid refrigerant maintains that surface at atemperature well below freezing, e.g. -20° F. to -25° F.

The discoid sides of drum 84 may be made of the same material as thedrum surface 84a. Preferably, however, they are made of a rigid,thermally insulating material such as a low temperature-resistantplastic material to minimize the energy required to cool the drum.Preferably also, the sides of the drum have a slightly larger diameterthan the surface 84a to provide circumferential flanges 84b at oppositesides of the drum for reasons that will become apparent later.

Drum 84 is rotated by an electric motor 106 mounted to support 82. Theshaft of motor 106 drives a timing chain or belt 108 which is trainedaround a pinion 110 rotatively fixed to axle 88. When motor 106 is inoperation, it rotates drum 84 at a selected speed, e.g. 5 to 40 rpm, inthe clockwise direction as viewed in FIG. 5.

Referring now to FIGS. 5 and 6, in apparatus 80, the product mix isatomized by air or other gas in a plural-port fitting 114. In theillustrated apparatus, the fitting is a T-fitting; but is could be aY-fitting or have some other plural port configuration. In any event,fitting 114 receives product mix, e.g., yogurt mix (Y), through its leg114a which is connected to the outlet of a cylindrical manifold 116which will be described in detail shortly. Suffice it to say at thispoint, the manifold has an axial passage 117, the outlet end of which isconnected to fitting leg 114a. Coupled to the inlet end of passage 117is a pipe 118 containing an in-line valve 122 and which leads down to apressurized container 124 supported by support 82 as shown in FIG. 4.Container 124 is of a type well known in the food industry. It isbasically a flexible bag for containing a liquid such as a yogurt mix.The bag is mounted inside a housing 125 which may be pressurized tocollapse the bag and force the liquid out through pipe 118 at a selectedpressure, e.g., 70 psi in the case of apparatus 80.

Fitting 114 receives air or other gas at one of its arms 114b. For this,that arm is connected to a pipe 126 containing an in-line electric valve128, the pipe leading down to an air compressor 132 supported on support82 next to the refrigeration unit 104 as shown in FIG. 4. Compressor 132delivers the gas at a suitable pressure, e.g. 50 psi.

The remaining arm 114c of fitting 114 is connected to one end of aturbulent mixing passage or conduit 138 whose opposite end is disposedover drum 84. Most preferably, that end of the turbulence conduitconnects to a fluid distributor 142 which is basically a short pipe withholes in it and which is spaced just above the drum surface 84a parallelto the drum axis. The function of the distributor 142 is to distributeaerated product mix issuing from conduit 138 relatively uniformly on thedrum surface 84a between flanges 84b when the drum is rotated. Anenclosure 153 surrounding the distributor confines the discharge fromthe distributor. The bottom edge of the enclosure is spaced slightlyabove the face of the drum (see FIG. 5), e.g. by 0.050" to therebyprovide a narrow passage 153a through which the product discharges toform a thin layer on the drum.

Thus, just as described above in connection with the FIG. 1 apparatus,the atomized mix in the mixing chamber defined by fitting 114 isdirected into turbulence conduit 138 where the fluids are subjected toconsiderable turbulence and buffeting because of passage through thatconduit. This encourages the formation of an agglomeration of productmix particles and flavoring and other additives while, at the same time,entrapping the air or the gas so that the gas is effectively containedwithin the particles. Consequently, the fluid issuing from thedistributor 142 is comprised of approximately uniformly sized, stillrelatively small aerated particles with the air enclosed within an outergenerally continuous "skin", all as described above in connection withFIG. 1. Also as described there, the conduit is dimensioned so that thefluid leaves the conduit at very low or nearly atmospheric pressure sothat there is minimum splatter. To help in this respect, the conduit 138may be provided with a bore that is tapered so as to become wider at itsdischarge end.

As noted earlier, the amount of aeration is a function of a number offactors, including particularly the density and viscosity of the mix,the length and inner diameter of the turbulence passage, and thevelocity of flow of the mix through the turbulent mixing passage. Thelatter is, in turn, strongly dependent on the driving pressure appliedto the mix. In the present case, for standard Elgin non-fat natural baseyogurt mixes and standard flavor syrups and a production rate of 0.8oz./sec. using a mix driving pressure on the order of 70 psi and airpressure of about 50 psi, we have found that optimum aeration (40%) isattained with a conduit length-to-diameter ratio on the order of 100 to200, e.g., 0.17 in. ID by 24 in. long. Lengths less than this, ofcourse, can be used to provide aeration percentages less than themaximum obtainable for a given mix and driving pressure, while lengthsgreater than this can be used to first mix and aerate the product andthen convey it to the desired location. The excess length, of course,will add nothing to the mixing, but will also not detract unduly fromthe product provided that it is not excessively long.

The discharge from distributor 142 is deposited onto drum 84 where itspreads out over the drum surface 84a forming a uniform coating thereonas the drum rotates. Since the surface 84a of the drum is maintained ata low temperature because of the refrigerant circulated through thedrum, that coating freezes immediately, forming on the drum surface a"skin" S of the frozen product, e.g. ice cream or yogurt.

As best seen in FIGS. 4 and 5, a doctor blade 146 is spaced angularlyaround the drum from distributor 142 and adjacent to the drum 84a sothat its edge 146a engages the drum surface 84a. Thus, the doctor bladeis able to scrape the frozen product skin S from the surface of the drumwhereupon the product may drop as a ribbon R into a container C placedon a shelf 148 under the drum as shown in FIG. 5. Preferably, the bladeedge 146a is formed with a V-shaped notch so that the edge "corrals" theedge margins of the skin and directs them toward the middle of the bladeso that the frozen product can drop into a container C having arelatively small mouth, e.g., a standard ice cream container or cone.

Apparatus 80 is provided with a housing shown in phantom at 152 (FIG. 5)which encloses drum 84, distributor 142 and doctor blade 146, anappropriate opening 152a being provided in a wall of housing 152 toprovide access to shelf 148 so that a cup C can be positioned on theshelf under the drum, as shown in FIG. 5.

In accordance with the invention, apparatus 80 also includes provisionfor selecting flavors of the yogurt or other product being dispensed bythe apparatus. The injection of the flavors occurs at manifold 116.

More particularly, the manifold is a conventional device which has, inaddition to the axial passage 117, a circumferential array of radialinjection ports. For purposes of illustration, the manifold is shown ashaving only three such ports, 116a, 116b and 116c for injecting threedifferent flavorings F₁, F₂ and F₃ into the yogurt mix Y. Each such portextends to the axial passage 117, so that the flavoring injected throughthat port is entrained in the fluid stream flowing through passage 117.Also, each port is provided with a check valve (not shown) to preventbackflow through that port.

Tubes or pipes 162a, 162b and 162c connect ports 116a, 116b and 116c,respectively, to pressurized syrup containers 164a, 164b and 164c,respectively, in a compartment 165 supported by support 82 next to theyogurt container 124. These containers may be similar to container 124.The tubes include in-line electrically operated valves 166a, 166b and166c, respectively, which control the flow of fluid from the containers164a, 164b and 164c to the corresponding injection ports of manifold116. The operation of these valves, as well as of valves 122 and 128controlling the flow of yogurt and air to the T-fitting 114, arecontrolled by output signals from a controller 172 which has anaccessible keypad 174a by which an operator can control the operation ofapparatus 80. Controller 172 may also control the status ofrefrigeration unit 104, air compressor 132 and the speed of the drumdrive motor 106. The containers 164 may be individually pressurized, orthey may be pressurized via compartment 165 which itself may bepressurized from an external source; the same is true for container 124.Advantageously, the compressor 132 supplies the requisite pressure forall the containers, as well as the mixing air to pipe 126.

Keypad 174 has selection keys or buttons 174a to 174c to enable theoperator to select among three flavors of the ice cream or yogurtproduct to be dispensed by the apparatus 80. Controller 172 isprogrammed so that when the operator presses one of the keys, e.g. key174a, the controller 172 applies timed actuating signals to valves 122and 166a thereby opening the valves. Resultantly, non-flavored yogurtmix flows through the manifold passage 117 and an additive, e.g. vanillasyrup, is injected by way of injection port 116a into passage 117 sothat that additive is entrained in the mix flowing through that passageto the T-fitting 114. The controller also applies a signal to open thevalve 128 so that compressed gas is introduced into the T-fitting 114,thereby producing a violent agitating and mixing action in the T-fitting114 which atomizes and aerates the product mix flowing from that fittingto the turbulence conduit 138. The signals from controller 172 thatcontrol valves 122, 128 and 166a cause those valves to remain open forthe time required for the apparatus 80 to dispense onto the rotatingdrum 84 a selected volume of aerated yogurt mix, e.g. one portion orserving of chocolate yogurt, that will fill the cup C on shelf 148. Thenthose valves dose so that substantially no additional fluid flowsthrough the conduit 138.

As soon as the product mix is dispensed onto drum 84, it freezes andforms a thin skin thereon. The skin is rotated around to the doctorblade 146 which scrapes the skin from the drum so that it falls intocontainer C.

When the container C has been filled, it can be removed and replaced byan empty cup. That cup can, in turn, be filled with a different flavoredyogurt, e.g. vanilla, by the operator depressing the appropriate key,say key 174b, of keypad 174.

As with the FIG. 1 apparatus 10, apparatus 80 may be arranged todispense different size product portions. Preferably, also, controller172 is programmed so that after each serving, valve 122 controlling theflow of gas to fitting 114 is opened while the drum 84 executes acomplete revolution. The gas clears the fitting 114, conduit 138 anddistributor 142 of product from the previous serving, while the doctorblade scrapes dean the entire surface 84a of drum 84 as it continues torotate. This ensures that there is minimal flavor carryover from oneproduct serving to the next and that the drum and fluid lines are clean.

Although in the apparatus 80 specifically illustrated herein, the flavoradditives are injected into the product mix stream via the axial passage117 of manifold 116, they could just as well be injected directly intothe air stream. This simply involves interchanging the positions ofpipes 118 and 126 so that air is supplied to passage 117, while productmix is supplied to the arm 114b of the T-fitting 114. That arrangementhas an advantage in that when the system is flushed out at the end ofeach dispensing cycle, the air flowing through pipe 118 will purge themanifold passage 117, the inner ends of the injection ports 116a to 116cand the leg 114a of the T fitting. Obviously in both arrangements, thevalves controlling the flow of product mix and additives should be asclose as possible to the fitting 114 and manifold passage 117 tominimize the standing volumes of product mix and additives afterpurging.

It will be appreciated also that flavor carryover may be eliminatedentirely by using, instead of the manifold 116, a separate T-fitting andturbulence conduit to dispense each of the three product flavors. Stillfurther, in some instances, it may be desirable to premix the flavoringand yogurt mix to provide three separate flavored yogurt mixes to thethree separate fittings and turbulence conduits. An arrangement such asthis is shown in FIG. 7. Three preflavored yogurt mixes are supplied viaseparate valves 166a, 166b and 166c to three T or Y fittings 114a, 114band 114c, respectively. These fittings have dedicated turbulenceconduits 138a, 138b and 138c leading to separate distributors 142a, 142band 142c positioned over drum 84 as shown. Thus with this embodiment,there can be no flavor carryover from one product serving to the next.

If desired, the apparatus 80 can be provided with the steam cleaning orsanitizing fluid feature described above in connection with apparatus 10and may also include the described dispenser for depositing nuts orother toppings onto the product in container C.

Apparatus 80 has all of the other advantages described above forapparatus 10 in that it produces a product which freezes instantly withessentially no large unpalatable ice crystals. Resultantly, the productdispensed to the container C is composed of very small aerated yogurtparticles freshly made to produce a product which is especiallyflavorful and palatable. As with apparatus 10, the aeration of theproduct is controlled primarily by the length of the turbulence conduit138. The degree of freezing may be controlled by varying one or morefactors such as the speed of the drum 84, the drum temperature or thethickness of the mix.

Refer now to FIG. 8 which shows apparatus for producing and dispensingfrozen products using flat cooling means to freeze the products. Theidentifying numerals in the figure are the same as those used for thecorresponding parts of the FIGS. 5 and 6 apparatus described above.

This system is basically the same as the one depicted in FIGS. 5 and 6except that it delivers the product, e.g., yogurt, and the gas through aplurality of valved lines to a plurality of mixing means 116 andturbulence tubes 138. The tubes 138 terminate in a head 202 whichincludes control buttons 202a for releasing product from a selected oneor more of the turbulence tubes 138.

Preferably, the pipes leading to tubes 138 are flexible so that anoperator can move the head over a cabinet 204 containing a thermallyconductive top plate 206. A refrigeration unit similar to unit 104 inFIG. 4 is situated in cabinet 204 for cooling plate 206 to a temperaturebelow freezing.

To use the FIG. 8 apparatus, the operator may press one (or more) of thebuttons 202a to discharge liquid yogurt having a particular flavor(s)onto plate 206. The yoghurt spreads out on the plate and freezes. Theoperator may then scrape the frozen product from the plate using ascraper 208 and deposit it in a suitable container. The procedure issimilar to making pancakes on a griddle using a bar-type drinkdispenser, except that the fluids being dispensed are different flavoredliquid desserts which are frozen on the plate 206.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description are efficiently attained. Also,certain changes may be made in carrying out the above method and in theconstruction set forth without departing from the scope of theinvention. For example, instead of using a two-fluid mixing chamber towhich gas is supplied under pressure, in some applications, it may bepractical to use a single-fluid nozzle or fitting and to draw in theaerating gas, e.g. air, through a vent in the nozzle or the fitting orthe turbulence conduit, as in a venturi.

Further, while the invention has been described with particularreference to the formation and dispensing of frozen foods such as yogurtand the like, it may also be utilized profitably in general tothoroughly mix one or more liquids with one or more fluids (gases orliquids). Thereafter, the temperature of the resultant product may bereduced to form a solid or semi-solid product in which one component isincorporated intimately in the other. Therefore, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the inventiondescribed herein.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:
 1. Apparatus for producing and dispensing anaerated food product comprisingmixing means for mixing a liquid and agas to produce an atomized fluid stream comprised of liquid particles;means defining a flow-through passage having an entrance end positionedto receive the fluid stream from the mixing means and an exit end spacedfrom the entrance end, said passage confining the flow of the fluid sothat the liquid particles coalesce and become aerated before the fluidleaves the passage through said exit end thereof; cooling means locatedadjacent to said passage defining means for at least partially freezingthe aerated fluid exiting said passage to form said food product; sourcemeans for providing a liquid to said mixing means in response to fluidpressure; a source of pressurized gas, and means for conducting said gasto said mixing means and to said source means so that said gas propelssaid liquid to said mixing means, atomizes the liquid in the mixingmeans and forces said atomized fluid stream through said passage so thata uniformly aerated fluid exits said passage.
 2. The apparatus definedin claim 1 and further includingflavoring source means responsive tofluid pressure for introducing liquid flavoring into said fluid beforesaid fluid stream exits said passage, and means for conducting said gasto the flavoring source means so that the flavoring is introduced intosaid fluid stream under pressure.
 3. The apparatus defined in claim 2wherein the flavoring is introduced into said liquid upstream from saidpassage.
 4. The apparatus defined in claim 2 wherein the flavoring isintroduced into the liquid from said source means.
 5. The apparatusdefined in claim 2 wherein the flavoring is introduced into the gas fromthe gas source.
 6. The apparatus defined in claim 2 wherein theflavoring source means comprisepressure vessel means connected to saidgas conducting means; a plurality of collapsible containers containingdifferent liquid flavorings positioned inside the pressure vessel meansand communicating with said passage, and means for controlling theliquid flow from each container to said passage so that the flavoringsfrom said containers can be introduced selectively into said fluidstream.
 7. The apparatus defined in claim 6 wherein said controllingmeans includetubes leading from said containers to said passage, andremotely controllable valves connected to said tubes for controllingfluid flow through said tubes into said fluid stream.
 8. The apparatusdefined in claim 7 and further includinganother remotely controllablevalve included in said conducting means between said gas source and saidmixing means for controlling gas flow to said mixing means, and afurther remotely controllable valve connected between said source meansand said mixing means for controlling the flow of liquid to said mixingmeans.
 9. The apparatus defined in claim 1 and further includingone ormore additional mixing means similar to said first-mentioned mixingmeans; one or more additional passage defining means similar to saidfirst-mentioned passage defining means for receiving the fluid streamfrom the corresponding one or more additional mixing means, said sourcemeans providing said liquid to all of said mixing means and saidconducting means conducting gas to all of said mixing means so that auniformly aerated fluid can exit each passage for freezing by thecooling means, and means for introducing a different fluid additive froma selection of additives into the fluid flowing through each passage.10. The apparatus defined in claim 9 and further including means forseparately controlling the fluid flow from each said passage to enablethe dispensing of food product with a selected additive.
 11. Theapparatus defined in claim 10 wherein the introducing meanscomprisepressure vessel means connected to said gas conducting means,and a plurality of collapsible containers containing different additivespositioned inside the pressure vessel means, each containercommunicating with a different passage.
 12. The apparatus defined inclaim 11 wherein said cooling means comprise a cold plate locatedadjacent to the exit ends of all of said passage defining means. 13.Apparatus for producing and dispensing an aerated food productcomprisingmixing means for mixing a liquid and a gas to produce anaerated fluid stream comprised of liquid particles; means defining aflow-through passage having an entrance end positioned to receive thefluid stream from the mixing means and an exit end spaced from theentrance end, said passage confining the flow of the fluid so that theliquid particles coalesce and become aerated before the fluid leaves thepassage through said exit end thereof; cooling means located adjacent tosaid passage defining means for cooling the aerated fluid exiting saidpassage to form said food product; source means for providing a liquidto said mixing means in response to fluid pressure; a source ofpressurized gas, and means for conducting said gas to said mixing meansand to said source means so that said gas propels said liquid to saidmixing means, aerates the liquid in said mixing means and forces theaerated fluid stream through said passage so that a uniformly aeratedfluid exits said passage.
 14. Apparatus for producing and dispensing anaerated food product comprisinga mixing chamber having first and secondinlets and an outlet; a source of pressurized gas; a small diameterconduit connected to the chamber outlet; a pressurizable source ofliquid product connected to the chamber first inlet; means for supplyinggas from said source to the second chamber inlet and to saidpressurizable source so that the same gas propels the liquid product tothe mixing chamber, aerates the liquid product in that chamber andforces the aerated liquid product through the conduit so that auniformly aerated liquid product is delivered from the conduit, andmeans for cooling the liquid product delivered from the conduit.
 15. Theapparatus defined in claim 14 and further including means for connectinga pressurizable source of additive to the chamber first inlet, andmeansfor connecting the gas source to the pressurizable source of additive soas to force that additive into the liquid product.
 16. Apparatus forproducing and dispensing an aerated food product comprisinga mixingchamber having first and second inlets and an outlet; a source ofpressurized gas; a small diameter conduit connected to the chamberoutlet; a pressurizable source of liquid product connected to thechamber first inlet; means for supplying gas from said source to thesecond chamber inlet and to said pressurizable source so that the samegas propels the liquid product to the mixing chamber, atomizes theliquid product in that chamber and forces the atomized liquid productthrough the conduit so that a uniformly aerated liquid product isdelivered from the conduit, and means for cooling the liquid productdelivered from the conduit to at least partially freeze said product.17. The apparatus defined in claim 16 and further includingmeans forconnecting a pressurizable source of additive to the chamber firstinlet, and means for connecting the gas source to the pressurizablesource of additive so as to force that additive into the liquid product.